1. Technical Field
The present invention relates to a backlight unit and a liquid crystal display having the same, and more particularly, to a backlight unit and a liquid crystal display device having the same capable of precisely defining a location of an optical sheet and preventing deformation of the sheet.
2. Discussion of the Related Art
A backlight unit is an element of a liquid crystal display (“LCD”) device that irradiates light at a rear surface of an LCD panel mounted in an LCD monitor, a personal computer, a navigation system for a vehicle, and the like. The LCD device displays various images and information. The LCD device uses a backlight unit for supplying light to the LCD panel because the LCD device is a passive display that does not emit light by itself.
The backlight unit includes a receiving member, a light source, a light guide plate, and a plurality of optical sheets. The receiving member receives the light guide plate and the optical sheets that include, for example, a reflection sheet, a diffusion sheet, a prism sheet, and a protection sheet.
The optical sheets deliver uniform light to the LCD panel. Therefore, a location where the optical sheets are initially mounted within the backlight unit preferably remains unchanged. An optical property is affected by the distance between the optical sheets and light guide plate.
Heat is generated from the light source during an operation of the backlight unit, thereby increasing the temperature of the backlight unit. Thin optical sheets experience changes in length by heat expansion. If the frame is not capable of accommodating for such changes in length, the optical sheets deform within the backlight unit. Such deformation may result in a change in distance between the optical sheet and light guide plate, thereby causing a display failure of the LCD device.
Tightly securing the optical sheets within the backlight unit to prevent the movement of the optical sheets can compromise the ability to maintain a sufficient distance between the optical sheets and the frame to sufficiently accept heat expansion of the optical sheets. As a result a way of preventing movement of the optical sheets while also maintaining sufficient distance between the optical sheets and the frame is required.